Demonstrations commemorating the second anniversary of the fatal shooting of a teenager by a policeman brought Athens and several other major cities to a standstill for several hours yesterday and were marred by outbreaks of violence. In Athens, where thousands of police officers were mobilized to avert a repeat of unprecedented rioting two years ago, around 6,000 schoolchildren, members of leftist organizations and labor unionists took to the streets in separate marches that were mostly peaceful. Some of the protesters chanted «Greece is not a protectorate» and held up banners saying «IMF out,» in reference to the International Monetary Fund, one of the debt-ridden government’s three creditors. In the early afternoon a few dozen youths hurled stones and chairs from street cafes at riot police officers who pushed them back. Some protesters threw red paint over bank facades and at policemen. Later in the day, a larger crowd of hooded youths threw firebombs and chunks of marble and paving stones at officers, who responded by firing tear gas. Police said at least three people were injured. These included a middle-aged man who was hit on the head by a rock, a younger man who was beaten up by a group of protesters that mistook him for an undercover police officer, and a woman who went into shock after a stun grenade went off next to her. Several store facades were smashed and garbage dumpsters set alight but the damage but was not extensive. Police said they had detained 40 people for questioning, chiefly suspected members of far-left organizations and anarchist groups. Small-scale outbreaks of violence were also reported during similar demonstrations in other major cities including Thessaloniki and the Cretan port of Hania.